Question: Is it better to eat directly after high intensity interval training (HIIT), or wait for two hours? I read that eating after exercise reduces human growth hormone and can reduce the effect of my training.
There is a lot of confusion around exercise and eating schedules. In this case, the confusion is in regards to the effect human growth hormone (hGH) has on your body. After any exercise, but especially high intensity exercise, hGH levels are significantly elevated. The problem is that eating directly following exercise appears to lower hGH levels.
Since hGH is important for ]muscular growth, it seems as if this is the last thing you’d want to happen after resistance training or HIIT. After all, you’ve just devoted time to increasing your fitness so you want that training to be as effective as possible, right?
To understand why the answer is actually “yes, you should eat directly after exercise”, we need to better understand why our body is releasing so much hGH in the first place. To understand this, we also need to bring a couple other hormones into the discussion.
Insulin’s Role in Exercise
Insulin is our “too much sugar” hormone. Our blood likes to have a very specific amount of sugar in it–too much is toxic, too little is dangerous. When our blood sugar increases, such as after a meal, insulin is released to clear the excess sugar away. For a healthy individual with no insulin resistance, most of that sugar gets escorted into the muscles where it is stored as glycogen (glycogen is a type of starch our body stores).
[quote align=”right” color=”#999999″]Insulin is actually our body’s best muscle-building hormone, not hGH![/quote]
If the amount of sugar is too much for our muscles to use, or the individual is insulin resistant, then more sugar gets stored as fat instead. From our body’s perspective, it’s better to store sugar as fat than have it floating around in the blood.
During high-intensity exercise, our body has extremely high requirements for carbohydrates. This is because only carbohydrates can be burned anaerobically (without oxygen). To deal with the increased demand for carbohydrates, our body releases the muscle glycogen it has stored. Unfortunately, during high-intensity intervals, we blow through that stored glycogen extremely quickly. Suddenly, our body needs to create more sugar so our blood sugar doesn’t drop too much.